Field of the Invention
The present disclosure relates to an image forming apparatus for forming images on a sheet, such as a printer, a copying machine, a multifunction peripheral and the like.
Description of the Related Art
An electrophotographic image forming apparatus performs image formation by forming a toner image on a photoreceptor and transferring the toner image to a sheet. The image forming apparatus is provided with a fixing device for fixing the toner image on the sheet by heating and pressurizing the toner image. To heat the toner image, the fixing device comprises a resistance heater as a heat source. Due to variation in resistance value, the resistance heaters have individual differences in heating value. In a conventional image forming apparatus, the resistance value of the resistance heater is detected by feeding a small current to the fixing device before starting to heat the resistance heater. Then, heating of the resistance heater is started with power according to a detection result. Japanese Patent Application Laid-open No. 2011-197372 discloses a fixing device including a non-volatile memory which stores characteristic information relating to the fixing device such as the resistance value of the resistance heater. The image forming unit obtains the characteristic information from the non-volatile memory before starting to heat the resistance heater. Then, according to the characteristic information obtained, the resistance heater of the fixing device is heated.
In a case where the fixing device is heated after obtaining the characteristic information stored in the fixing device, it is not necessary to detect the resistance value of the resistance heater before starting to heat the resistance heater. In terms of cost, inexpensive non-volatile memory, transfer rate of which is about 100 kbps, is used as the non-volatile memory provided in the fixing device. Thereby, in a case where heating of the resistance heater is started after completing reading of the characteristic information, by the time heating of the resistance heater is started, standby time is caused, which hampers rapid heating of the fixing device. Thereby, an image forming apparatus capable of heating the heater of the fixing device comprising a storage unit which stores the characteristic information more rapidly than before is desired.